It sounds suspicious to me as UBS can easily check both companies exist and a agency agreement should be fairly straightforward, so maybe this one is not or maybe there is suspicion of VAT or tax avoidance or evasion. I would want a very carefully worded engagement letter and AML checks and then a very large fee in advance before doing anything to cover time spent dealing with that and getting full details of the agreement and transactions it covers. I suggest you get more information.